U.S. patent application number 16/778963 was filed with the patent office on 2021-08-05 for validation of fluid level sensors.
The applicant listed for this patent is PRATT & WHITNEY CANADA CORP.. Invention is credited to Benjamin BREGANI, Sean MCCARTHY.
Application Number | 20210239510 16/778963 |
Document ID | / |
Family ID | 1000004669623 |
Filed Date | 2021-08-05 |
United States Patent
Application |
20210239510 |
Kind Code |
A1 |
BREGANI; Benjamin ; et
al. |
August 5, 2021 |
VALIDATION OF FLUID LEVEL SENSORS
Abstract
Methods and systems for validating a fluid level sensor having a
floating element are provided. First readings are acquired from the
fluid level sensor indicative of fluid levels sensed via the
floating element during a first period of operation of the fluid
level sensor. A validated range of fluid levels for the fluid level
sensor is determined based on the first readings. At least one
second reading is acquired from the fluid level sensor during a
second period of operation, subsequent to the first period of
operation. A starting position of the floating element for the
second period of operation is determined based on the at least one
second reading. When the starting position of the floating element
is within the validated range, validating the at least one second
reading.
Inventors: |
BREGANI; Benjamin;
(Montreal, CA) ; MCCARTHY; Sean; (Beaconsfield,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PRATT & WHITNEY CANADA CORP. |
Longueuil |
|
CA |
|
|
Family ID: |
1000004669623 |
Appl. No.: |
16/778963 |
Filed: |
January 31, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01F 25/0069 20130101;
G01F 23/74 20130101; G01F 23/686 20130101 |
International
Class: |
G01F 25/00 20060101
G01F025/00; G01F 23/68 20060101 G01F023/68; G01F 23/74 20060101
G01F023/74 |
Claims
1. A method for validating a fluid level sensor having a floating
element; comprising: acquiring first readings from the fluid level
sensor indicative of fluid levels sensed via the floating element
during a first period of operation of the fluid level sensor;
determining a validated range of fluid levels for the fluid level
sensor based on the first readings; the validated range bounded by
an upper bound and a lower bound and being contained within a range
of values of the first readings; acquiring at least one second
reading from the fluid level sensor during a second period of
operation, subsequent to the first period of operation;
determining; based on the at least one second reading, a starting
position of the floating element for the second period of
operation; and when the starting position of the floating element
is within the validated range, validating the at least one second
reading.
2. The method of claim 1, wherein determining the validated range
comprises: determining the upper bound of the validated range based
on a maximum reading of the first readings; determining the lower
bound of the validated range based on a minimum reading of the
first readings; and establishing the validated range as located
between the upper bound of the validated range and the lower bound
of the validated range.
3. The method of claim 2, wherein determining the validated range
further comprises appending the validated range to a
previously-validated range determined during at least one previous
periods of operation preceding the first period of operation.
4. The method of claim 1, further comprising, when the starting
position of the floating element is outside the validated range:
estimating a subsequent fluid level based on the first readings and
a duration of the first period of operation; and assigning the
estimated subsequent fluid level as a starting fluid level for the
second period of operation.
5. The method of claim 4, further comprising: comparing the
starting fluid level to a predetermined minimum fluid level; and
raising an alert when the starting subsequent fluid level is below
the predetermined minimum fluid level.
6. The method of claim 5, wherein the predetermined minimum fluid
level is determined based on an estimated duration of the second
period of operation.
7. The method of claim 4, further comprising obtaining a duration
of the first period of operation.
8. The method of claim 1, further comprising, when the starting
position of the floating element is outside the validated range,
raising an alert invalidating the at least one second reading.
9. The method of claim 8, wherein raising the alert comprises
providing an indication of a maintenance operation to be performed
on the fluid level sensor.
10. The method of claim 1, further comprising resetting the
validated range following a maintenance operation being performed
on the fluid level sensor.
11. A system for validating a fluid level sensor having a floating
element, comprising: a processing unit; and a non-transitory
computer-readable medium having stored thereon instructions
executable by the processing unit for: acquiring first readings
from the fluid level sensor indicative of fluid levels sensed via
the floating element during a first period of operation of the
fluid level sensor; determining a validated range of fluid levels
for the fluid level sensor based on the first readings, the
validated range bounded by an upper bound and a lower bound and
being contained within a range of values of the first readings;
acquiring at least one second reading from the fluid level sensor
during a second period of operation, subsequent to the first period
of operation; determining, based on the at least one second
reading, a starting position of the floating element for the second
period of operation; and when the starting position of the floating
element is within the validated range, validating the at least one
second reading.
12. The system of claim 11, wherein determining the validated range
comprises: determining the upper bound of the validated range based
on a maximum reading of the first readings; determining the lower
bound of the validated range based on a minimum reading of the
first readings; and establishing the validated range as located
between the upper bound of the validated range and the lower bound
of the validated range.
13. The system of claim 12, wherein determining the validated range
further comprises appending the validated range to a
previously-validated range determined during at least one previous
periods of operation preceding the first period of operation.
14. The system of claim 11, further comprising, when the starting
position of the floating element is outside the validated range:
estimating a subsequent fluid level based on the first readings and
a duration of the first period of operation; and assigning the
estimated subsequent fluid level as a starting fluid level for the
second period of operation.
15. The system of claim 14, further comprising: comparing the
starting fluid level to a predetermined minimum fluid level; and
raising an alert when the starting subsequent fluid level is below
the predetermined minimum fluid level.
16. The system of claim 15, wherein the predetermined minimum fluid
level is determined based on an estimated duration of the second
period of operation.
17. The system of claim 14, further comprising obtaining a duration
of the first period of operation.
18. The system of claim 11, further comprising, when the starting
position of the floating element is outside the validated range,
raising an alert invalidating the at least one second reading.
19. The system of claim 18, wherein raising the alert comprises
providing an indication of a maintenance operation to be performed
on the fluid level sensor.
20. The system of claim 11, further comprising resetting the
validated range following a maintenance operation being performed
on the fluid level sensor.
Description
TECHNICAL FIELD
[0001] The present disclosure relates generally to fluid level
sensors, and specifically to validation of fluid level sensors.
BACKGROUND OF THE ART
[0002] Fluid level sensors have long been used in a variety of
applications, including in various types of vehicles, such as
automobiles, ships, and aircraft. As the most common form of fuel
for such vehicles is liquid, such as petroleum-based fuel, fluid
level sensors are used to provide information regarding a remaining
stock of fuel, to avoid fuel shortage situations. In addition to
fuel levels, the levels of various other fluids, such as coolant,
lubricant, and the like, may also be of interest, and fluid level
sensors are often used to inform operators and/or service personnel
of remaining quantities of the various fluids, for instance to
avoid shortages.
[0003] While existing fluid level sensors are suitable for their
intended purpose, it may be desirable to validate the operation of
fluid level sensors. In some cases, accessing a fluid level sensor
during operation can be difficult.
[0004] As such, there is room for improvement.
SUMMARY
[0005] In accordance with at least one broad aspect, there is
provided a method for validating a fluid level sensor having a
floating element. First readings are acquired from the fluid level
sensor indicative of fluid levels sensed via the floating element
during a first period of operation of the fluid level sensor. A
validated range of fluid levels for the fluid level sensor is
determined based on the first readings, the validated range bounded
by an upper bound and a lower bound and being contained within a
range of values of the first readings. At least one second reading
is acquired from the fluid level sensor during a second period of
operation, subsequent to the first period of operation. A starting
position of the floating element for the second period of operation
is determined based on the at least one second reading. When the
starting position of the floating element is within the validated
range, validating the at least one second reading.
[0006] In accordance with another broad aspect, there is provided a
system for validating a fluid level sensor having a floating
element. The system comprises a processing unit, and a
non-transitory computer-readable medium having instructions stored
thereon. The instructions are executable by the processing unit
for: acquiring first readings from the fluid level sensor
indicative of fluid levels sensed via the floating element during a
first period of operation of the fluid level sensor; determining a
validated range of fluid levels for the fluid level sensor based on
the first readings, the validated range bounded by an upper bound
and a lower bound and being contained within a range of values of
the first readings; acquiring at least one second reading from the
fluid level sensor during a second period of operation, subsequent
to the first period of operation; determining, based on the at
least one second reading, a starting position of the floating
element for the second period of operation; and when the starting
position of the floating element is within the validated range,
validating the at least one second reading.
[0007] Features of the systems, devices, and methods described
herein may be used in various combinations, in accordance with the
embodiments described herein.
DESCRIPTION OF THE DRAWINGS
[0008] Reference is now made to the accompanying figures in
which:
[0009] FIG. 1 is a cutaway side view of an example fluid level
sensor;
[0010] FIG. 2 are multiple cutaway side views of the example fluid
level sensor of FIG. 1 at different fluid levels;
[0011] FIG. 3A is a cutaway side view of the example fluid level
sensor of FIG. 1 having a validated starting position;
[0012] FIG. 3B is a cutaway side view of the example fluid level
sensor of FIG. 1 having a non-validated starting position;
[0013] FIG. 4 is a flowchart of an example method for validating a
fluid level sensor; and
[0014] FIG. 5 is a block diagram of an example computing device for
implementing the method of FIG. 4.
[0015] It will be noted that throughout the appended drawings, like
features are identified by like reference numerals.
DETAILED DESCRIPTION
[0016] A fluid level sensor can serve to provide information about
the quantity of fluid present in a reservoir. The reservoir can be
any suitable kind of reservoir, and can be used to store any
suitable kind of fluid, including fuels, lubricant, coolant, fluid
for consumption, for use in industrial processes, and the like.
Depending on the nature of the fluid in the reservoir, the
embodiments of fluid level sensors disclosed herein can be packaged
in protective casings or otherwise shielded from the fluid using
any suitable techniques.
[0017] With reference to FIG. 1, there is shown a fluid level
sensor 110 disposed in a reservoir 102. The reservoir 102 contains
a certain quantity of a fluid 105. The reservoir 102 can have any
suitable shape and size, and is formed to contain the fluid 105. In
some embodiments, the reservoir 102 is substantially closed,
thereby substantially completely encapsulating the fluid 105 and,
optionally, the fluid level sensor 110. In some other embodiments,
the reservoir 102 is partially open, for instance at a top surface
thereof, via which fluid 105 can be added to the reservoir 102. The
reservoir 102 is provided with a fluid output 104, via which the
fluid 105 can be fed from the reservoir 102 to other systems. For
example, if the reservoir 102 is an oil reservoir for an engine,
the fluid output 104 can serve to provide a flow of fluid 105, for
instance oil, to the engine. The flow of the fluid 105 from the
reservoir 102 can be controlled via pumps, valves, or other fluidic
systems, as appropriate.
[0018] The fluid level sensor 110 can be affixed to the reservoir
102 in any suitable fashion. In some cases, the fluid level sensor
110 is affixed to the reservoir 102 via a lid or other top surface
of the reservoir. For example, the lid of the reservoir 102 can
have defined therein an aperture for receiving the fluid level
sensor 110. In some other cases, the fluid level sensor 110 is
affixed to a side wall of the reservoir 102. In still other cases,
the fluid level sensor 110 is retained within the reservoir 102 in
some other fashion.
[0019] The fluid level sensor 110 is composed of a sensing circuit
112 and floater 114, which are retained within and/or on a sensor
structure 116. The sensor structure 116 can be a tubular member or
other elongated structure for receiving, retaining, and/or
supporting the sensing circuit 112 and the floater 114, as
appropriate. For instance, the sensing circuit 112 can be disposed
within a tubular cavity of the sensor structure 116, and the
floater 114 can be provided with an aperture through which the
sensor structure 116 is insertable, such that the floater 114 is
retained by the sensor structure on an outer surface thereof. Other
configurations are also considered. For instance, the floater 114
can be retained by the sensor structure 116, and the sensing
circuit can be disposed on an inner or an outer surface of the
reservoir 102.
[0020] The floater 114 moves along a floater path, illustrated by
arrow 115, in response to changes in the quantity of fluid 105 in
the reservoir 102. The floater path defines the range of motion of
the floater 114, hereinafter referred to as the floater range 115.
The floater 114 can be any suitable device which exhibits buoyancy
when placed in the fluid 105. In some embodiments, the floater 114
is hollow, or contains a hollow area, to provide buoyancy. In some
embodiments, the floater 114 is a plastic disk. In other
embodiments, the floater is a plastic cylinder. Still other types
of floaters 114 are considered.
[0021] In addition, the floater 114 is provided with one or more
elements which produce a stimuli which will interact with elements
of the sensing circuit 112, as will be described in greater detail
hereinbelow. In some embodiments, the floater 114 is provided with
magnetic elements which produce a magnetic field. In other
embodiments, the floater 114 is provided with various electrical
elements which produce an electric field. In further embodiments,
the floater 114 is provided with optical elements. For example, the
floater 114 is provided with light-emitting elements which emit a
particular type of light, for instance ultraviolet, visible, or
infrared light. In another example, the floater 114 is provided
with one or more reflective elements which reflect light provided
within the reservoir 102, for example from a light source. Still
other types of elements are considered, and in some other
embodiments the floater 114 combines a plurality of types of
elements.
[0022] The sensing circuit 112 is composed of a plurality of
passive elements in a first branch of the sensing circuit 112, and
of a plurality of switching elements disposed between the first
branch and a second branch of the sensing circuit 112. Sensing
terminals are arranged at corresponding ends of the first and
second branches of the sensing circuit 112. The passive elements
can be any suitable passive element, including resistors,
capacitors, inductors, and the like. The passive elements can be of
any suitable value: in some embodiments, all of the passive
elements are substantially of the same value (e.g., each
100.OMEGA., each 10 .mu.F, each 10 mH, etc.); in other embodiments,
the passive elements can be assigned different values. The passive
elements can be connected to one another in any suitable fashion,
including using a breadboard, on a printed circuit-board, and the
like.
[0023] The switching elements can be any device which actuates a
switch between an open and a closed state in response to external
stimuli. The switching elements can respond to magnetic, electric,
optical, or other stimuli, as appropriate, based on the particular
stimuli produced by the floater 114. For example, if the floater
104 includes a magnetic element, suitable for producing a magnetic
field, the switching elements 136 are magnetically-switched
elements, which change their state, for instance from open to
closed, when the floater 104 is proximate to the switching elements
136. In another example, the floater 104 includes an optical
element producing optical stimuli, and the switching elements 136
include optically-switched elements, for instance based on
photodiodes.
[0024] The fluid level sensor 110 detects the level of the fluid
105 within the reservoir 102 based on the movement of the floater
114 within the reservoir 102. As the floater 114 moves, the stimuli
produced by the floater 114 will cause different ones of the
switching elements within the sensing circuit 112 to switch. Since
altering which of the switching elements is closed alters the
configuration of the sensing circuit 112, the effective value of
the passive elements as sensed from the sensing terminals will
vary. This variation can then be correlated with the level of the
fluid 105 with the reservoir 102. In some embodiments, a controller
150 is communicatively coupled to the fluid level sensor 110, for
instance to the sensing circuit 112, to obtain information about
the level of the fluid 105 within the reservoir 102. The controller
150 can be associated with the reservoir 102, or with a larger
system of which the reservoir 102 is an element. For instance, the
reservoir 102 can serve to provide the fluid 105 to an engine or
other system, and the controller 150 can be a controller for the
engine. Other types of systems are also considered. For instance,
the aforementioned engine can be an engine of an aircraft, which
can include one or more engines, and the reservoir 102 and supply
fuel to the one or more engines of the aircraft.
[0025] With continued reference to FIG. 1, in some embodiments a
"low fluid level" 120 can be defined for the reservoir 102, for
instance by the controller 150. The low fluid level 120 can be any
suitable predefined level for the fluid 105. For example, the low
fluid level 120 can be associated with a minimum level of the fluid
105 for the controller to authorize certain operations.
Alternatively, or in addition, the low fluid level 120 can be
associated with a level of fluid below which the reservoir 102
should not be permitted to be used. When the controller 150 detects
the fluid level at or below the low fluid level 120, the controller
150 can raise an alert, indicate that a maintenance operation be
performed, or the like.
[0026] For example, the reservoir 102 is an oil reservoir for an
engine of an aircraft or other vehicle, and the low fluid level 120
is a "low oil level". The controller 150 can be configured for
validating whether the level of the fluid 105 within the reservoir
102--in this case, oil--is above the low oil level prior to, or at
the time of, starting the engine associated therewith. When the
controller 150 determines that the oil level is above the low oil
level, the controller 150 can indicate to an operator of the engine
and/or the aircraft that a suitable level of oil is within the
reservoir 102. Conversely, when the controller 150 determines that
the oil level is below, or optionally at, the low oil level 120,
the controller 150 can indicate to an operator of the engine and/or
the aircraft that the reservoir 102 does not contain a sufficient
amount of oil, and halt starting of the engine, recommend a
maintenance action, or otherwise alert an operator of the engine or
aircraft that the amount of oil remaining in the reservoir is below
the low oil level.
[0027] In configurations in which the floater 114 is retained in
some fashion via the sensor structure 116, it can occur that
movement of the floater 114 along the floater range 115 is
obstructed. For instance, debris, residue, or other particulate
matter within the fluid 105 can become lodged between the floater
114 and the sensor structure 116. As a result, the floater 114 can
remain at a level along the floater range 115 which is above the
current level of the fluid 105 within the reservoir 102. This can
result in the fluid level sensor 110 providing inaccurate readings
to the controller 105, including readings indicating that the level
of the fluid 105 within the reservoir 102 is higher than the actual
level of the fluid. It should be noted that the floater 114 can
also become obstructed in other configurations. For instance,
similar particulate matter can cause the floater 114 to become
caught on a side wall of the reservoir 102, or on another structure
within the reservoir 102, which in turn can obstruct proper
movement of the floater. Described herein are systems and methods
for validating a fluid level sensor having a floating element, for
instance the floater 114. The techniques described herein are
applicable to a variety of configurations of the fluid level sensor
110, in which movement of the floater 114 can be obstructed, and
serve to validate the readings provided by the fluid level sensor
110, for instance to the controller 150.
[0028] With reference to FIG. 2, the reservoir 102 is illustrated
in three different states, indicated at 202, 204, and 206
(collectively "the states 202-206"). Each of the states 202-206 is
associated with a different level of the fluid 105: in state 202,
the fluid 105 is at a higher level than in states 204, 206; in
state 206, the fluid 105 is at a lower level than in states 202,
204; and the level of the fluid 105 in state 204 is intermediate to
the level of the fluid 105 in states 202, 206. The states 202-206
are indicative of how the level of the fluid 105 can vary over
time, for instance during operation of a system (engine, aircraft,
or otherwise) of which the reservoir 102 is an element.
[0029] For example, state 202 indicates the level of the fluid 105
at the start of a period operation for the reservoir 102. Over
time, the fluid 105 is consumed, exiting the reservoir 102 via
fluid output 104, for instance to be provided to an engine,
aircraft, or other system. The fluid 105 can be consumed by engine
or aircraft, whether as part of its normal operation, or as part of
a so-called "gulping" process, by which a rapid intake of the fluid
105 from the reservoir 102 is performed at the start of a period of
operation. Variations in temperature, air pressure, and altitude
can also change the density of the fluid 105, which can in turn
result in changes in the level of the fluid 105. At a later time,
the reservoir 102 can be in the state 204, and/or at the state 206.
In some cases, fluid can circulate back to the reservoir 102, for
instance after a filtering process. As a result, the reservoir 102
can successively pass between one or more of the states 202-206, as
well as to any number of intermediate states associated with other
levels for the fluid 105.
[0030] As the level of the fluid 105 in the reservoir 102 changes,
the floater 114 can be detected by the controller 150 as having
traversed a portion of the floater range 115, based on the readings
produced by the fluid level sensor 110. The portion of the floater
range 115 which is traversed by the floater 114 is indicative of
the range of levels for the fluid 105 which were reported by the
fluid level sensor 110 in the form of readings provided to the
controller 150. The controller 150 uses the readings produced by
the fluid level sensor 110 to determine a validated range for the
fluid level sensor, indicated by the bounded range 210.
[0031] The validated range 210 for the fluid level sensor 110 is
bounded by an upper value and a lower value, and can be determined
in various fashions. In some embodiments, the readings obtained by
the controller 150 during a first period of operation (for
instance, aligning with the states 202-206) are analyzed to
determine maximum and minimum readings obtained by the controller
150. The validated range 210 can then be set as the range bounded
by the maximum and minimum readings, corresponding to the upper and
lower values bounding the validated range 210.
[0032] In some other embodiments, the readings obtained by the
controller 150 during the first period of operation are analyzed,
and a predetermined number of maximum and minimum values are
discarded, for instance to limit the risk of outliers being used
when setting the validated range 210. The upper and lower bounds
for the validated range 210 can then be set by remaining maximum
and minimum values, after discarding the predetermined number of
values. In some other embodiments, the readings obtained by the
controller 150 are analyzed statistically in one or more fashions,
and the validated range 210 is set based on the statistical
analysis. For example, readings corresponding to values outside a
predetermined number of standard deviations from the mean can be
discarded. In another example, a mean value for the readings is
calculated, and the validated range 210 is set as a particular
percentage of the range of readings obtained by the controller 150.
Other approaches are also considered.
[0033] In some situations, the validated range 210 determined
during a particular period of operation can be concatenated with
other validated ranges determined during previous periods of
operation. For instance, in cases in which the validated range 210
overlaps at least partially with previously-validated ranges for
the fluid level sensor 110, the validated range 210 and the
previously-validated ranges can be concatenated to produce a
broader validated range for the fluid level sensor. Alternatively,
or in addition, if the period of operation associated with the
validated range 210 occurred in close temporal proximity to
previous periods of operations, having respective associated
validated ranges, the validated ranges can be concatenated. For
instance, if a shutdown period for a system of which the reservoir
102 is an element between a previous period of operation and the
period of operation associated with the validated range 210 is
below a predetermined threshold, the validated range 210 can be
concatenated with the previously-validated range. Other approaches
are also considered.
[0034] In some embodiments, when a maintenance operation is
performed on the reservoir 102, the controller 150 is programmed to
cancel, delete, or otherwise reset any previously-determined
validated ranges. The maintenance operation can include servicing
the reservoir 102 and/or the fluid level sensor 110, adding or
removing fluid from the reservoir 102, and the like. These
maintenance operations can, in some instances, result in the
addition of debris to the reservoir 102, which can in turn result
in the floater 114 becoming obstructed as it travels the floater
range 115. As a result, the controller 150 is configured to reset
any previously-stored validated ranges following a maintenance
operation.
[0035] The process of determining a validated range for the fluid
level sensor 110 can be repeated, with or without concatenation,
for every period of operation in which the reservoir 102 and the
fluid level sensor 110 are used. Every validated range serves, at
least, for the following period of operation of the reservoir 102
and the fluid level sensor 110, and can be used to assess whether
readings from the fluid level sensor 110 are valid or not.
[0036] With reference to FIGS. 3A-B, there are illustrated two
states 302, 304 for the reservoir 102 at the start of a subsequent
period of operation, that is to say, a second period of operation
subsequent to a first period of operation in which the validated
range 210 is determined. The first period of operation can, for
instance, be associated with a first flight performed by an
aircraft in which the reservoir 102 is disposed, and the second
period of operation can be associated with a second, subsequent
flight, which the aircraft is about to embark upon. Other
operational contexts are also considered.
[0037] In FIG. 3A, at the start of the second period of operation
in state 302, the controller obtains one or more readings from the
fluid level sensor 110. The controller 150 determines a starting
position for the floater 114 based on the readings, illustrated
here as element 310. The starting position 310 is a position along
the floater range 115 and/or along the validated range 210 which is
substantially commensurate with the position of the floater 114 at
the start of the second period of operation. It should be noted,
however, that when operations begin within the engine or other
system of which the reservoir 102 is an element, variations in the
level of the fluid 105 can occur, and that in some cases the
starting position 310 as determined by the controller 150 is not
strictly defined as the absolute position of the floater 114 at the
start of the second period of operation.
[0038] The controller 150 then compares the starting position 310
of the floater 114 to the validated range 210. When the starting
position 310 of the floater 114 falls within the validated range
210, as illustrated in FIG. 3A, then the readings provided to the
controller 150 by the fluid level sensor 110 during the second
period of operation are considered to be valid. The validated range
210 is based on the controller 150 having determined that the
floater 114 can move unobstructed within the validated range 210
during the previous period of operation (associated with the states
202-206 of FIG. 2). As a result, when the starting position 310 of
the floater 114 is found within the validated range 210 at the
start of the second period of operation, the controller 150 can
infer that the floater 114 can at least move without obstruction
through the validated range 210. The controller 150 can
additionally infer, based on readings produced by the fluid level
sensor 110 during the second period of operation, the extent of a
subsequent validated range for the second period of operation, and
can optionally concatenate the subsequent validated range to the
validated range 210 from the first period of operation.
[0039] In some embodiments, after validating the second readings
from the fluid level sensor 110, the controller 150 can issue an
alert or indication, for instance to an operator of the engine or
aircraft of which the reservoir 102 is an element, indicating that
the fluid level sensor 110 has been validated. In other
embodiments, the controller 150 can block or withhold authorization
of one or more operations, for instance starting an engine or
permitting takeoff of an aircraft, until the readings from the
fluid level sensor 110 are validated. Once the readings from the
fluid level sensor 110 are validated, the controller 150 can
authorize the operations to occur or be implemented.
[0040] In FIG. 3B, the controller 150 can similarly obtain one or
more readings from the fluid level sensor at the start of the
second period of operation, in state 304. The controller 150
determines a starting position for the floater 114 based on the
readings, illustrated here as element 320. Because the starting
position 320 for the floater 114 in state 304 is outside the
validated range 210, the controller 150 does not know whether the
region around the starting position for the floater 114 could
potentially inhibit movement of the floater 114 along the floater
range 115. As a result, the controller 150 does not validate the
second readings provided by the fluid level sensor 110.
[0041] In some embodiments, when the starting position 320 for the
floater 114 during the second period of operation is outside the
validated range 210, obtained from the previous period of
operation, an alert is raised, for instance by the controller 150.
The alert can be raised for an operator of an engine, aircraft, or
other system of which the reservoir 102 is an element. For example,
a light indicator, audible alarm, textual alert, or the like, can
be presented to the operator. In another example, the alert can
indicate a maintenance action that should be performed on the fluid
level sensor 110 and/or on the reservoir 102. Other types of alerts
are also considered.
[0042] In some other embodiments, the controller 150 is configured
to estimate the fluid level within the reservoir 102 at the start
of the second period of operation in response to failing to
validate the second readings. The controller 150 uses the level of
the fluid 105 at the start of the first period of operation (e.g.,
the fluid level in state 202 of FIG. 2) and the duration in time of
the first period of operation to estimate the level of fluid 105
that remains at the end of the first period of operation. For
example, the controller 150 can maintain a log of the duration (in
hours, minutes, seconds, or the like) for each of the periods of
time during which the system for which the reservoir 102 is an
element was operational. In the case of an aircraft, the controller
150 can maintain a log of the duration of each flight mission, for
instance in a database or other memory store. In another example, a
flight log can be accessible to the controller 150, which can
retrieve information on the duration of past flight missions.
[0043] For example, the reservoir 102 is used as part of an engine
of an aircraft, and the controller 150 can use a standard value for
the amount of the fluid 105 that is used by the engine per hour
under normal operating conditions. The estimated amount of used
fluid is subtracted from the amount of the fluid 105 that was
present at the start of the first period of operation to estimate
the amount of the fluid 105 that remained at the end of the first
period of operation. Since the first and second period of
operations follow one another, the amount of fluid 105 remaining at
the end of the first period of operation should be substantially
equivalent to the amount of fluid 105 that is present at the start
of the second period of operation. The controller 150 can thus
assign the estimated level of the fluid 105 as a starting fluid
level for the second period of operation, and discard the second
readings provided by the fluid level sensor.
[0044] In some embodiments, the controller 150 can then use the
estimated starting fluid level for the second period of operation
to determine whether the level of the fluid 105 in the reservoir
102 is above the low fluid level 120. For example, the low fluid
level 120 can be a minimum level of oil which must be present for
an aircraft to be permitted to perform a flight mission. When the
estimated starting oil level is above the low oil level 120, the
controller 150 can indicate, for instance to an operator of the
aircraft, that while the readings of the fluid level sensor 110
cannot be validated, the estimated level of oil within the
reservoir 102 is above the low oil level, and the flight mission
can proceed. Alternatively, when the estimated starting oil level
is below the low oil level 120, the controller 150 can raise an
alert indicating to the operator that the flight mission cannot
proceed, and that there is a risk of a low oil level within the
reservoir 102. Other approaches are also considered.
[0045] In some embodiments, the process of estimating the starting
fluid level for the second period of operation is performed in a
conservative manner, for instance by using worst-case scenario
calculations for the estimated amount of fluid consumption during
the first period of operation. In some other embodiments, the
estimated starting fluid level is compared against a variable low
fluid level 120, which can be based on an estimated duration for
the second, subsequent period of operation. For instance, the
second period of operation can be associated with a flight mission
having an estimated duration, and the low fluid level 120 can be
calculated based on an estimated amount of the fluid 105 which will
be used during the second period of operation.
[0046] Although the foregoing discussion focuses primarily on
accounting for situations in which the floater 114 is obstructed
and unable to move along the floater range 115, it should be noted
that the systems and methods described herein can also be used to
validate readings from a fluid level sensor, for instance the fluid
level sensor 110, in the event of a failure of the sensing circuit
112. This can include switches which can be stuck open or stuck
short, switches which are damaged, non-responsive passive elements,
and the like. The methods and systems described herein can also be
used to validate readings for the fluid level sensor 100 in the
event of the floater 114 losing the ability to produce stimuli
which affects the sensing circuit 112, for instance becoming
demagnetized.
[0047] With reference to FIG. 4, there is provided a method 400 for
validating a fluid level sensor having a floating element, for
instance the fluid level sensor 110 with the floater 114. At step
402, during a first period of operation, first readings from the
fluid level sensor 110 are acquired. The first readings can be
acquired, for example, by a controller associated with the fluid
level sensor, for instance the controller 150. The first readings
can include any suitable number of readings and can be acquired at
any suitable frequency and in any suitable format.
[0048] At step 404, a validated range of fluid levels for the fluid
level sensor 110 is determined based on the first readings, for
instance the validated range 210. The validated range is bounded by
an upper bound and a lower bound, and is contained within a range
of values of the first readings. For example, the upper bound can
correspond to a maximum value of the first readings, and the lower
bound can correspond to a minimum value of the first readings.
Other approaches are also considered.
[0049] At step 406, during a second period of operation subsequent
to the first period of operation, at least one second reading is
acquired from the fluid level sensor 110. The second readings can
be any suitable number of readings, and can be acquired similarly
to the first readings.
[0050] At step 408, a starting position for the floater 114 for the
second period of operation is determined based on the at least one
second reading. In some embodiments, the starting position is
identified as the first one of the second readings produced by the
fluid level sensor 110. In some other embodiments, the starting
position is identified as an average of a plurality of first ones
of the second readings. In some further embodiments, the starting
position is estimated based one or more first ones of the second
readings. Other approaches are also considered.
[0051] At decision step 410, a determination is made regarding
whether the starting position for the floater 114 for the second
period of operation is within the validated range 210. When the
starting position is within the validated range 210, the method 400
proceeds to step 412. When the starting position is not within the
validated range 210, the method proceeds to one or more of steps
420, 422, and 424. It should be noted that although each of steps
420, 422, and 424 are optional, certain embodiments of the method
400 will include at least one of the steps 420, 422, 424.
[0052] At step 412, when the starting position of the floater 114
is found to be within the validated range, the second readings
produced by the fluid level sensor 110 are validated. In some
embodiments, this involves the controller 150 issuing an indication
to an operator that the fluid level sensor 110 has been validated.
In some other embodiments, validating the second readings results
in other operations being performed by the controller 150.
[0053] Optionally, when the starting position is not within the
validated range 210, the method proceeds to step 420. At step 420,
an alert is raised to invalidate the at least one second reading.
For example, the controller 150 can raise an alert, which can be
presented to the operator. In some embodiments, the alert indicates
a maintenance operation or other corrective action to be performed
in order to address the lack of validation of the second
readings.
[0054] Optionally, when the starting position is not within the
validated range 210, the method proceeds to step 422;
alternatively, the method 400 can move from step 420 to step 422,
in embodiments in which step 420 is performed. At step 422, a
subsequent fluid level is estimated based on the first readings and
a duration of the first period of operation. The subsequent fluid
level is indicative of the level of the fluid 105 within the
reservoir 102 at the start of the second period of operation, and
can be estimated using values for the average or worst-case
consumption of the fluid 105 during the first period of operation.
The duration of time of first period of operation can be known to
the controller 150, or can be obtained from a database or other
data store, as appropriate.
[0055] Optionally following step 422, at step 424, the estimated
subsequent fluid level is assigned as a starting fluid level for
the second period of operation. The starting fluid level can then
be compared to a predetermined minimum fluid level, for instance
the low fluid level 120. The low fluid level 120 can be fixed, or
can be based on an estimated duration of the second period of
operation. If the starting fluid level is found to be below the low
fluid level 120, an alert can be raised indicating that the level
of the fluid 105 within the reservoir 102 is insufficient or
unsafe.
[0056] With reference to FIG. 5, the method 400 may be implemented
by a computing device 510, which can embody part or all of the
controller 150. The computing device 510 comprises a processing
unit 512 and a memory 514 which has stored therein
computer-executable instructions 516. The processing unit 512 may
comprise any suitable devices configured to implement the
functionality of the controller 150 and/or the functionality
described in the method 400, such that instructions 516, when
executed by the computing device 510 or other programmable
apparatus, may cause the functions/acts/steps performed by the
controller 150 and/or described in the method 400 as provided
herein to be executed. The processing unit 512 may comprise, for
example, any type of general-purpose microprocessor or
microcontroller, a digital signal processing (DSP) processor, a
central processing unit (CPU), an integrated circuit, a field
programmable gate array (FPGA), a reconfigurable processor, other
suitably programmed or programmable logic circuits, custom-designed
analog and/or digital circuits, or any combination thereof.
[0057] The memory 514 may comprise any suitable known or other
machine-readable storage medium. The memory 514 may comprise
non-transitory computer readable storage medium, for example, but
not limited to, an electronic, magnetic, optical, electromagnetic,
infrared, or semiconductor system, apparatus, or device, or any
suitable combination of the foregoing. The memory 514 may include a
suitable combination of any type of computer memory that is located
either internally or externally to device, for example
random-access memory (RAM), read-only memory (ROM), compact disc
read-only memory (CDROM), electro-optical memory, magneto-optical
memory, erasable programmable read-only memory (EPROM), and
electrically-erasable programmable read-only memory (EEPROM),
Ferroelectric RAM (FRAM) or the like. Memory 514 may comprise any
storage means (e.g., devices) suitable for retrievably storing
machine-readable instructions 516 executable by processing unit
512.
[0058] It should be noted that the computing device 510 may be
implemented as part of a FADEC or other similar device, including
electronic engine control (EEC), engine control unit (EUC), engine
electronic control system (EECS), and the like. In addition, it
should be noted that the techniques described herein can be
performed by the controller 150 substantially in real-time, during
operation of the engine 100, for example during a flight
mission.
[0059] The methods and systems for validating a fluid level sensor
having a floating element, as described herein, may be implemented
in a high level procedural or object oriented programming or
scripting language, or a combination thereof, to communicate with
or assist in the operation of a computer system, for example the
computing device 510. Alternatively, the methods and systems
described herein may be implemented in assembly or machine
language. The language may be a compiled or interpreted
language.
[0060] Embodiments of the methods and systems described herein may
also be considered to be implemented by way of a non-transitory
computer-readable storage medium having computer instructions
and/or a computer program stored thereon. The computer program may
comprise computer-readable instructions which cause a computer, or
more specifically the processing unit 512 of the computing device
510, to operate in a specific and predefined manner to perform the
functions described herein, for example those described in the
method 400.
[0061] Computer-executable instructions may be in many forms,
including program modules, executed by one or more computers or
other devices. Generally, program modules include routines,
programs, objects, components, data structures, etc., that perform
particular tasks or implement particular abstract data types.
Typically the functionality of the program modules may be combined
or distributed as desired in various embodiments.
[0062] The embodiments described in this document provide
non-limiting examples of possible implementations of the present
technology. Upon review of the present disclosure, a person of
ordinary skill in the art will recognize that changes may be made
to the embodiments described herein without departing from the
scope of the present technology. Yet further modifications could be
implemented by a person of ordinary skill in the art in view of the
present disclosure, which modifications would be within the scope
of the present technology.
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